The invention is directed to wideband, high power, nonlinear amplifiers, and particularly to the linearization of such amplifiers.
The linearization of high power microwave amplifiers used in satellite earth stations has received much attention recently, since such amplifiers presently have to be operated below saturation in their linear region which is inefficient and expensive, or use microwave implementations of linearizers which are expensive to manufacture. One example of an implementation of microwave predistortion is found in the publication by G. Satoh et al, entitled "Nonlinear Satellite Channel Design for QPSK/TDMM Transmission", Fifth International Conference on Digital Communications by Satellite, Genoa, Italy, 1981, pp 47-54. The predistortion circuit has a characteristic which approaches the inverse of that of the high power amplifier. Because of the physical limitation on the power output of the amplifier, at the best, the characteristics of a soft limiter can be obtained for the cascade of the predistortion linearizer and the memoryless nonlinear amplifier.